How much less case capacity?

I just tried to drop my usual 42.9 grains into a case... and it was well up into the neck of the case. I dropped the charge down to 41.7, and it was just at the bottom of the case (and no longer near a compressed load).

I was using H4895, this is .308 caliber, 168 gr Match Kings.

I didn't think there was going to be THAT much of a difference in case capacity... That was a full grains worth of powder difference.

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gamestalker

November 5, 2011, 07:11 PM

If a powder is in it's normal charge range, and has been worked up properly, then a compressed charge is as pressure safe as a non compressed charge. Most of the loads I work up for high powered rifle are slow burning powders for that application, and compressed. It's not velocity I'm seeking when compressing charges, but consistent pressure curves, which result in consistent velcoities. If all other elements of the round are consistent, so will be your accuracy and velocity.

I'm assuming your LC brass is new? That being so is going to also have an effect on case capacity because the brass has not yet been formed. But one must consider where your pressures are with the other brass. If you've been running max or near max, you'll do right by re-working that charge, and not just to manage possible pressure issues, but also to find that sweet spot, different brass, different results.

scythefwd

November 5, 2011, 08:51 PM

Game -The brass is fired, just not by me. I have to full length size either way as I'm shooting a break action. That's a whole nother beast.. stout stuff this LC match.

Anyways... My regular brass gets a middle of the road 43 or 42.9 grains of H4895. It isn't compressed. It shoots well enough for me.

This brass got a charge of 43 grains and I had to dump it.. it was into the neck.

I ended up going with 41.7 (.7 grains above minimum) and I'll monitor for crated/flattened primers. I'm not sure how many loadings this stuff will take... but I bet I get 7 or 8 out of em. Easily twice as thick as the regular brass... and it requires some real umph to size (my press doesn't have compound leverage).

USSR

November 5, 2011, 08:52 PM

I have and shoot a lot of Lake City M118 brass. As you have noticed, it has a reduced case capacity in comparison to commercial .308 brass. I have found that ~42.0 grains of 4895 is where you want to stop when loading 168 grain bullets in Lake City Match brass.

Don

gamestalker

November 5, 2011, 09:52 PM

You'll do well then to reduce and work back up, considering it is brass from another firearm of unknown # of reloadings. You seem to have pretty good handle on what your doing, so just keep an eye open for signs and you'll do just fine.

scythefwd

November 5, 2011, 10:59 PM

game.. this stuff isn't going to let go any time soon... Usually you have signs that the brass is having issues before it lets go... case head thinning, really flattened primers, etc... that show it's been abused.

This stuff looks like its been rolled in the dirt, but dimensionally it's awesome.

It's so thick, that it literally pulled my expander ball out of my die. I have this thing cranked down on to remove crimped primers... I actually had to cut the case apart to get my expander back lol. It was sprayed down with some oneshot and let sit for about 5 minutes... It feels like I'm resizing magnum cases... not the wimpy .308 cases. Man I wish my press had compound leverage.

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